// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/controls/menu/menu_scroll_view_container.h"

#include "base/macros.h"
#include "third_party/skia/include/core/SkPaint.h"
#include "third_party/skia/include/core/SkPath.h"
#include "ui/accessibility/ax_view_state.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/color_palette.h"
#include "ui/views/border.h"
#include "ui/views/bubble/bubble_border.h"
#include "ui/views/controls/menu/menu_config.h"
#include "ui/views/controls/menu/menu_controller.h"
#include "ui/views/controls/menu/menu_item_view.h"
#include "ui/views/controls/menu/submenu_view.h"
#include "ui/views/round_rect_painter.h"

using ui::NativeTheme;

namespace views {

namespace {

    static const int kBorderPaddingDueToRoundedCorners = 1;

    // MenuScrollButton ------------------------------------------------------------

    // MenuScrollButton is used for the scroll buttons when not all menu items fit
    // on screen. MenuScrollButton forwards appropriate events to the
    // MenuController.

    class MenuScrollButton : public View {
    public:
        MenuScrollButton(SubmenuView* host, bool is_up)
            : host_(host)
            , is_up_(is_up)
            ,
            // Make our height the same as that of other MenuItemViews.
            pref_height_(MenuItemView::pref_menu_height())
        {
        }

        gfx::Size GetPreferredSize() const override
        {
            return gfx::Size(MenuConfig::instance().scroll_arrow_height * 2 - 1,
                pref_height_);
        }

        bool CanDrop(const OSExchangeData& data) override
        {
            DCHECK(host_->GetMenuItem()->GetMenuController());
            return true; // Always return true so that drop events are targeted to us.
        }

        void OnDragEntered(const ui::DropTargetEvent& event) override
        {
            DCHECK(host_->GetMenuItem()->GetMenuController());
            host_->GetMenuItem()->GetMenuController()->OnDragEnteredScrollButton(
                host_, is_up_);
        }

        int OnDragUpdated(const ui::DropTargetEvent& event) override
        {
            return ui::DragDropTypes::DRAG_NONE;
        }

        void OnDragExited() override
        {
            DCHECK(host_->GetMenuItem()->GetMenuController());
            host_->GetMenuItem()->GetMenuController()->OnDragExitedScrollButton(host_);
        }

        int OnPerformDrop(const ui::DropTargetEvent& event) override
        {
            return ui::DragDropTypes::DRAG_NONE;
        }

        void OnPaint(gfx::Canvas* canvas) override
        {
            const MenuConfig& config = MenuConfig::instance();

            // The background.
            gfx::Rect item_bounds(0, 0, width(), height());
            NativeTheme::ExtraParams extra;
            extra.menu_item.is_selected = false;
            GetNativeTheme()->Paint(canvas->sk_canvas(),
                NativeTheme::kMenuItemBackground,
                NativeTheme::kNormal, item_bounds, extra);

            // Then the arrow.
            int x = width() / 2;
            int y = (height() - config.scroll_arrow_height) / 2;

            int x_left = x - config.scroll_arrow_height;
            int x_right = x + config.scroll_arrow_height;
            int y_bottom;

            if (!is_up_) {
                y_bottom = y;
                y = y_bottom + config.scroll_arrow_height;
            } else {
                y_bottom = y + config.scroll_arrow_height;
            }
            SkPath path;
            path.setFillType(SkPath::kWinding_FillType);
            path.moveTo(SkIntToScalar(x), SkIntToScalar(y));
            path.lineTo(SkIntToScalar(x_left), SkIntToScalar(y_bottom));
            path.lineTo(SkIntToScalar(x_right), SkIntToScalar(y_bottom));
            path.lineTo(SkIntToScalar(x), SkIntToScalar(y));
            SkPaint paint;
            paint.setStyle(SkPaint::kFill_Style);
            paint.setAntiAlias(true);
            paint.setColor(config.arrow_color);
            canvas->DrawPath(path, paint);
        }

    private:
        // SubmenuView we were created for.
        SubmenuView* host_;

        // Direction of the button.
        bool is_up_;

        // Preferred height.
        int pref_height_;

        DISALLOW_COPY_AND_ASSIGN(MenuScrollButton);
    };

} // namespace

// MenuScrollView --------------------------------------------------------------

// MenuScrollView is a viewport for the SubmenuView. It's reason to exist is so
// that ScrollRectToVisible works.
//
// NOTE: It is possible to use ScrollView directly (after making it deal with
// null scrollbars), but clicking on a child of ScrollView forces the window to
// become active, which we don't want. As we really only need a fraction of
// what ScrollView does, so we use a one off variant.

class MenuScrollViewContainer::MenuScrollView : public View {
public:
    explicit MenuScrollView(View* child)
    {
        AddChildView(child);
    }

    void ScrollRectToVisible(const gfx::Rect& rect) override
    {
        // NOTE: this assumes we only want to scroll in the y direction.

        // If the rect is already visible, do not scroll.
        if (GetLocalBounds().Contains(rect))
            return;

        // Scroll just enough so that the rect is visible.
        int dy = 0;
        if (rect.bottom() > GetLocalBounds().bottom())
            dy = rect.bottom() - GetLocalBounds().bottom();
        else
            dy = rect.y();

        // Convert rect.y() to view's coordinates and make sure we don't show past
        // the bottom of the view.
        View* child = GetContents();
        child->SetY(-std::max(0, std::min(child->GetPreferredSize().height() - this->height(), dy - child->y())));
    }

    // Returns the contents, which is the SubmenuView.
    View* GetContents()
    {
        return child_at(0);
    }

private:
    DISALLOW_COPY_AND_ASSIGN(MenuScrollView);
};

// MenuScrollViewContainer ----------------------------------------------------

MenuScrollViewContainer::MenuScrollViewContainer(SubmenuView* content_view)
    : content_view_(content_view)
    , arrow_(BubbleBorder::NONE)
    , bubble_border_(NULL)
{
    scroll_up_button_ = new MenuScrollButton(content_view, true);
    scroll_down_button_ = new MenuScrollButton(content_view, false);
    AddChildView(scroll_up_button_);
    AddChildView(scroll_down_button_);

    scroll_view_ = new MenuScrollView(content_view);
    AddChildView(scroll_view_);

    arrow_ = BubbleBorderTypeFromAnchor(
        content_view_->GetMenuItem()->GetMenuController()->GetAnchorPosition());

    if (arrow_ != BubbleBorder::NONE)
        CreateBubbleBorder();
    else
        CreateDefaultBorder();
}

bool MenuScrollViewContainer::HasBubbleBorder()
{
    return arrow_ != BubbleBorder::NONE;
}

void MenuScrollViewContainer::SetBubbleArrowOffset(int offset)
{
    DCHECK(HasBubbleBorder());
    bubble_border_->set_arrow_offset(offset);
}

gfx::Size MenuScrollViewContainer::GetPreferredSize() const
{
    gfx::Size prefsize = scroll_view_->GetContents()->GetPreferredSize();
    gfx::Insets insets = GetInsets();
    prefsize.Enlarge(insets.width(), insets.height());
    return prefsize;
}

void MenuScrollViewContainer::Layout()
{
    gfx::Insets insets = GetInsets();
    int x = insets.left();
    int y = insets.top();
    int width = View::width() - insets.width();
    int content_height = height() - insets.height();
    if (!scroll_up_button_->visible()) {
        scroll_view_->SetBounds(x, y, width, content_height);
        scroll_view_->Layout();
        return;
    }

    gfx::Size pref = scroll_up_button_->GetPreferredSize();
    scroll_up_button_->SetBounds(x, y, width, pref.height());
    content_height -= pref.height();

    const int scroll_view_y = y + pref.height();

    pref = scroll_down_button_->GetPreferredSize();
    scroll_down_button_->SetBounds(x, height() - pref.height() - insets.top(),
        width, pref.height());
    content_height -= pref.height();

    scroll_view_->SetBounds(x, scroll_view_y, width, content_height);
    scroll_view_->Layout();
}

void MenuScrollViewContainer::OnNativeThemeChanged(
    const ui::NativeTheme* theme)
{
    if (arrow_ == BubbleBorder::NONE)
        CreateDefaultBorder();
}

void MenuScrollViewContainer::OnPaintBackground(gfx::Canvas* canvas)
{
    if (background()) {
        View::OnPaintBackground(canvas);
        return;
    }

    gfx::Rect bounds(0, 0, width(), height());
    NativeTheme::ExtraParams extra;
    const MenuConfig& menu_config = MenuConfig::instance();
    extra.menu_background.corner_radius = menu_config.corner_radius;
    GetNativeTheme()->Paint(canvas->sk_canvas(),
        NativeTheme::kMenuPopupBackground, NativeTheme::kNormal, bounds, extra);
}

void MenuScrollViewContainer::GetAccessibleState(
    ui::AXViewState* state)
{
    // Get the name from the submenu view.
    content_view_->GetAccessibleState(state);

    // Now change the role.
    state->role = ui::AX_ROLE_MENU_BAR;
}

void MenuScrollViewContainer::OnBoundsChanged(
    const gfx::Rect& previous_bounds)
{
    gfx::Size content_pref = scroll_view_->GetContents()->GetPreferredSize();
    scroll_up_button_->SetVisible(content_pref.height() > height());
    scroll_down_button_->SetVisible(content_pref.height() > height());
    Layout();
}

void MenuScrollViewContainer::CreateDefaultBorder()
{
    DCHECK_EQ(arrow_, BubbleBorder::NONE);
    bubble_border_ = nullptr;

    const MenuConfig& menu_config = MenuConfig::instance();

    int padding = menu_config.use_outer_border && menu_config.corner_radius > 0
        ? kBorderPaddingDueToRoundedCorners
        : 0;

    int top = menu_config.menu_vertical_border_size + padding;
    int left = menu_config.menu_horizontal_border_size + padding;
    int bottom = menu_config.menu_vertical_border_size + padding;
    int right = menu_config.menu_horizontal_border_size + padding;

    if (menu_config.use_outer_border) {
        SkColor color = GetNativeTheme()
            ? GetNativeTheme()->GetSystemColor(
                ui::NativeTheme::kColorId_MenuBorderColor)
            : gfx::kPlaceholderColor;
        SetBorder(views::Border::CreateBorderPainter(
            new views::RoundRectPainter(color, menu_config.corner_radius),
            gfx::Insets(top, left, bottom, right)));
    } else {
        SetBorder(Border::CreateEmptyBorder(top, left, bottom, right));
    }
}

void MenuScrollViewContainer::CreateBubbleBorder()
{
    bubble_border_ = new BubbleBorder(arrow_,
        BubbleBorder::SMALL_SHADOW,
        SK_ColorWHITE);
    SetBorder(scoped_ptr<Border>(bubble_border_));
    set_background(new BubbleBackground(bubble_border_));
}

BubbleBorder::Arrow MenuScrollViewContainer::BubbleBorderTypeFromAnchor(
    MenuAnchorPosition anchor)
{
    switch (anchor) {
    case MENU_ANCHOR_BUBBLE_LEFT:
        return BubbleBorder::RIGHT_CENTER;
    case MENU_ANCHOR_BUBBLE_RIGHT:
        return BubbleBorder::LEFT_CENTER;
    case MENU_ANCHOR_BUBBLE_ABOVE:
        return BubbleBorder::BOTTOM_CENTER;
    case MENU_ANCHOR_BUBBLE_BELOW:
        return BubbleBorder::TOP_CENTER;
    default:
        return BubbleBorder::NONE;
    }
}

} // namespace views
